The sensitivity of separation discrimination to spatiotemporal jitter.
Differences of less than 20 sec of visual angle in the separation of a pair of closely spaced parallel lines can be reliably detected. This ability is known as a hyperacuity because the thresholds are smaller than the diameter of one foveal cone. It is shown that this ability does not require a stationary pattern. Indeed, correlated horizontal jitter of the line pair has little detrimental effect on performance for jitter that ranges up to 8 min arc for two lines with a separation of only 6 min arc. Uncorrelated jitter of the two lines, which allows the actual separation to vary from moment to moment, causes performance to deteriorate at a rate similar to the rise of signal uncertainty. The results reflect the operation of a system which is not only extremely robust to oculomotor instability but is also robust to positional variation that could not be produced by eye movements.
Badcock
D R
DR
Department of Psychology, University of Melbourne, Parkville, Victoria, Australia.
Wong
T L
TL
D004192:Discrimination, Psychological / Q000502:physiology; D006801:Humans; D008297:Male; D009068:Movement; D010364:Pattern Recognition, Visual / Q000502:physiology; D012684:Sensory Thresholds / Q000502:physiology; D013997:Time Factors; D014792:Visual Acuity / Q000502:physiology*